Brake-pipe vent-valve



T. H. THOMAS.

BRAKE PIPE VENT VALVE. APPLICAHON HLED AUG.2h

' i920. 1,384,930 Emma July 19,1921,

2 2 H lfJ- Tc "I" I2 -23 I 2:; '10 2: E f; i l 1 INVENTOR THGMAS H.THOMAS BYwW ATTORNEY cans svve HOUSE AIR BRAKE" corn-may, TION or PENNSY VANIA;

isnakn rirn vzelvr-vnhvnj To all whom it may concern:

c it known that l, THOMAS ll. a citizen of the United lfidgewood, in the county of State oi l' ennsylvania, have invented new and useful Improvements in Brake-Pipe l mit-Valves, of which the following is a specification. I

This invention relates to fluid pressure brakes, and more particularly to a brake pipe vent valve device.

lt'has heretofore been proposed to pro- Triorms,

Allegheny and vide a brake pipe vent valve device having a x is first moved to release brake pipe when not desired or piston subjectto the opposing pressures of the brake pipe and a quick action chamber which is adapted to be charged with fluid under pressure from the bral-ie pipe and valve means operatedby said piston upon a rcductioi'i in brake pipe pressure at an emergency rate for effecting the operation of a brake pipe vent valve.

in releasing the brakes, the brake valve position, in which fluid is supplied to the brake pipe at a pressure higher than the nessurmso as to secure a prompt and rapid increase in brake pipe pressure throughout the train and then the brake valve is moved to running position in which' he pressure of tluid supplied to the brake pipe is limited to the standardbrake pipe pressure and the overcharge 1n brake pipepressure at the head end of the train settles down to the standard pressure or even less. It the quick action chamber were allowed to become overcharged from the brake pipe, then when the brake valve is moved from release to running position, the fall of the brake pipe pressure may be at a suilicicnt rate to cause the movement of the emergentpiston to emergency position, thus causing an cmergencvventing of fluid from the intended. of the quick action The overcharging prevented by chamber has been heretofore restricting the communication through which the quick action chamber is charged from the brake pipe, so that the quick action chamber will not have time to become overcharged during the interval in which the brake pipe pressure is settling down to the standard pressure.

it has been found, however, that in some cases leakage past the piston rings of the Specification of LettersPate-nt; Application fileddAilgust 21, 1920.

States, residing at V the opposite side of the standard brake pipe Serial N0.*"4O5,014.

emergency piston inaddition'to the flowoit' fluid through the recharging passage may be suliicient to eiiect' the. overcharging of the qu i ck action chamber.

he principal object ofmy invention is to provide a brake pipevent' valve device having means for overcoming the above difficulty. c H

In the accom 'aanyingid airing, the single figure ls a. sectional view of vent valve; device, embodying myinvention. 1

As shown in the drawing, the brake pipe vent valve device may-comprise a casing 1, interposedin the brake pipe 2, so that the chamber 3 therein forms a conduit for the flow: of fluid under pressure throughthe Y brake pipe.

A'piston chamber 4 inth'ecasing, connected by her 3, containsan emergency piston G and the pressure of avalve chamber 7, containingv a slide valve '8, adapted to. be operated by piston 6, and connected by apassage 9' to a quick action chamber. 10. p

he casing 1 also has a valve chamber 11, connected by passage 12 to the brake pipe chamber 3 valve. 13 adapted to be chamber having a passage16, leading to the seatoi' emergency slide valve 8.

Mounted in the piston Gris a. stop 17, acted upon by a light spring 18, for yieldin gly de fining theiservice positions of thepiston 6 and slide valve 8, andmountecl in the piston stem 19 is a stop 20, acted upon by aspring 21. i I

1nthe release, position of the piston 6, as shown in the drawing, a quick actien chamber charging passage 22 is opened, said passage having a restricted port 23, leading; to piston chamber 4: and containing a ball check valve 24, for preventing back flow from valve chamber 7 to the piston chamber l, a choke plug 25, having a restricted port, being interposed in said passage, below the check valve 24.

In order to prevent leakage of fluid underpressure past the piston 6 to the valve chamber 7, when the brake pipe is overcharged in releasing the brakes, the piston 6 is provided with a seal 26 adapted to engage a seat ring 27.

Patentetl lliily 19, 1921'.

a brake pipe piston is subject to T and containing a brake pipe vent operated bya piston it contained in piston chamber 15, said passage 5 to the brakepipecham- In operation, the piston chamber 4 is charged from sage '5, and. through 4 passage 22, past charging the valve chamber 7, and the qulck action chamber 10, through passage 9.

fluid under pressure flows Upon a gradual service rate of reduction H in brake pipepressure, the piston 6 moves out until the" stop17 engages the casing,

and in this position, a port 28 registers with a. passage 29. Fluid under pressureis then vented from valve chamber 7 and quick ac tion chamber 10, to the atmospheric exhaust port 30 of the .quick action valve l3,at a

rate suflicient to prevent the further movement of the piston to emergency 'POSlblOIl;

valve chamber 7 g-Upon' a .suddenfemergency rate of reduction in brake pipe pressure, the piston 6 is moved out to emergency position, compressing the spring 18, and the slide valve 8 is moved so that passage 1G is connected to Fluid under pressure is then supplied to piston chamber 15 and the .I claim as new and desire to secure by to open the vent valve pistonl l is operated "from the brake pipe 13 g and vent fluid through passage Upon increasing the brake pipe pressure to effect the release ofthe brakes, the piston 6 will beshifted'to its. extreme inner position, inwhich .theseat 26 engages the seating ring 27., so'that possible leakage from piston chamber 4*, past the piston, to the valve chamber 7 vis prevented and conse- 1 quently the quick action chamber 10 cannot be overcharged.

When the pressure in the brake pipesettles back to the standard pressure,the spring .21 Will act to move the piston G slightly away from the seat ring 27, so that the .fullarea of the piston 6 will be subject to the pressure in valve chamber 7 and the desired sensitiveness of the piston 6 to'movement will be retained. 1

Having now describedmy invention,\vliat Letters Patent, 1S

1. In a fluid pressure brake, the combi my hand. of the brake pipe a nation with a brake pipe, a piston subject to the opposingpressures and a chamber adapted the brake pipe through pas-4 check valve 24,

adapted v 12 toff'the exhaust port 30, so that a local reduction in brake pipe pressure is effected.

. opposite. sides of to be charged from the brake pipe, and means operated by said piston for venting fluid from the brakepipe, of; means operated upon increasing the brake pipe pressure to e'flect the release of the brakes, for preventing leakage of fluid from the brake pipe past the piston to said chamber. I

' 2. In a fluid pressure'brake, the combination With a brake pipe, a piston subject to the opposing pressures of g the brake pipe and a chamber adaptedto be charged Il'OIli the brake pipe,-and means operated by said piston for venting fluid from the'brake pipe, of a seat on said piston and a seating ring to be engaged by said seat upon movement of said piston by an increase in brake pipe pressure to thereby prevent leakage from the brake pipe past the piston to'said chamber.

3. In a fluid pressure nation with a brake pipe, a valve device for venting fluid from the brake pipe, a piston subject to the opposing pressures of the brake pipe and a chamber having a passage for charging the chamber from the brake pipe, and a valve operated by said piston for varying the fluid pressure on. said valve device, of means ifor makinga tight seal at the piston upon movement of the piston under anincrease in thereby prevent leakage of fluid-from the brake pipe around the piston to said chamof means for making a fluid tight seal at the piston to prevent leakage of fluid around the piston from the. brake pipe to said chamber upon increasing the brake pipe pressure and a yielding stop for 'moving said piston away from its seal upon substantial. equalization of fluid pressures on g the piston. a

In testimony whereof I have hereunto set' 'TnoMAs H, 'ri oMAs.

brake, the combibrake pipe pressure, to

,90 piston for venting fluid from the brake pipe, 

